Problem: $ { \left[\begin{array}{rr}{-1} & {3} \\ {1} & {1} \\ {-2} & {3}\end{array}\right]+\left[\begin{array}{rr}{0} & {3} \\ {-1} & {0} \\ {0} & {0}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}+{0} & {3}+{3} \\ {1}+{-1} & {1}+{0} \\ {-2}+{0} & {3}+{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-1} & {6} \\ {0} & {1} \\ {-2} & {3}\end{array}\right]}$